Tasmania, south of Australia

Tasmanian Temperate Forests are found in the east and north east of Tasmania, extending offshore onto the Flinders and King Islands in the Bass Strait. The dry eucalyptus forest here differs greatly from cool, wet western Tasmania and has more affinities with mainland Australia. The forests here have been extensively altered by humans, first by Aboriginal fire regimes, and then by European settlement. As a result this ecoregion is the most degraded in Tasmania, and endemic species such as the Tasmanian thylacine (Thylacinus cynocephalus) and the King Island emu (Dromaius ater) are now extinct.

Scientific Code

(AA0412)

Ecoregion Category

Australasia

Size

7,000 square miles

Status

Critical/Endangered

Habitats

Description Location and General DescriptionEastern Tasmania differs greatly from western Tasmania, and is largely low-lying, with the granitic Ben Lomond Mountains as the only significant area of relief. The Legges Tor summit here is the second highest point in Tasmania at 1,572 m. Areas of lower elevation largely consist of post Carboniferous sediments overlying a basement of Cambrian rocks, with significant intrusions of Jurassic dolerite. Rainfall is low, from 400 mm to 1,000 mm per annum, and falls mostly in light showers, with the heaviest rainfall received in autumn or spring. Rainfall distribution has no pronounced seasonal minimum and is extremely variable when compared to the more predictable precipitation in the west (Jackson 1999b). Although still infertile by world standards, soils here are generally higher in nutrient content than those in western Tasmania, especially the rich soils on dolerite substrate (Jackson 1999a).

Flinder Island, along with two smaller islands, Cape Barren and Clark Islands, make up the Furneaux Group. King Island is a low plateau with rolling hills and a substrate composed of metamorphic rocks. In contrast, the mountainous Furneaux Group are part of a ridge of Devonian granites that reach from Victoria to the Ben Lomond Mountains of north-eastern Tasmania. The highest point on Flinders Island is 756 m in the Strzelecki Peaks (Hope 1974). Rainfall in the Bass Strait declines moving west to east, following the same gradient seen in Tasmania. King Island receives the highest rainfall in the Bass Strait, more than 1,000 mm per annum in the south (Hope 1974).

On Tasmania, vegetation of this ecoregion largely consists of open, or dry, sclerophyll forest and heath. Vegetation here is similar to that found on the Australian mainland, and a more complex mix of communities is seen than in western Tasmania, largely as a result of fire. The Tasmanian Temperate Forest ecoregion has been burned repeatedly by Tasmanian Aborigines for the last 12,000 years, encouraging open grassland savanna and the predominance of fire-adapted vegetation (Jackson 1999b). The cessation of Aboriginal burning after European arrival changed vegetation again, transforming grassy woodlands to shrubby forests (Duncan 1999).

Dry eucalypt forests are very open, typically dominated by peppermint eucalypts (subgenus Monocalyptus series Piperitae) more than 5 m in height, with a scattered layer of small xerophytic species, such as Acacia, Allocasuarina, and Exocarpos spp. in the understory Eucalyptus amygalina, E. pulchella, and E. viminalis are all found in this ecoregion. The upper slopes of Ben Lomond contain vegetation more similar to western Tasmania: wet eucalypt forest and rainforest, with alpine vegetation in the highest regions. Eucalyptus globulus, E. brookeriana, and E. regnans are all found in wet sclerophyll forest in this ecoregion (Jackson 1999a). Before European settlement, vegetation on the Bass Strait islands was mostly dry sclerophyll woodland, forest, and heath. Wetter areas on King Island had wet sclerophyll forest and limited rainforest elements, but most of this vegetation has been destroyed since European settlement. Many of the smaller islands are now dominated by Poa poiformis tussock grasslands (Hope 1974).

Low, dry woodlands of Allocasuarina and Callitris spp. are found on the Furneaux Group and along the east coast of Tasmania. Allocasuarina verticillata grows in low woodlands, sometimes in monospecific stands, then merging with Eucalyptus viminalis-E.globulus woodland. Shrubby Callitris oblonga is restricted to dry sites on Tasmania, whereas C. rhomboidea may grow to 30 m in fire-protected sites on Tasmania and the Furneaux Group. Both of these genera are very sensitive to fire disturbance (Jackson 1999a).

Biodiversity FeaturesTasmania is currently separated from mainland Australia by the Bass Strait which is 240 km wide at its narrowest and less than 70 m deep at its shallowest. Tasmania first became cut off from the mainland in the Miocene (Green 1974), but as sea levels fluctuated, Tasmania was reconnected to the mainland for varying periods of time. As sea levels fluctuated during glaciations in the Pleistocene the empty Bass Strait served as a land bridge, although it was likely arid and limited migration to specialized biota (Duncan 1999). Tasmania and the major islands in the Bass Strait were only finally isolated from mainland Australia roughly 13,000 years ago (Rawlinson 1974).

Partially as a result of this land bridge connecting the two, and partially because of the similar climate shared between the two regions, the Tasmanian Temperate Forest has strong affinities with the flora on southeastern mainland Australia. All vascular genera found in dry sclerophyll forest on Tasmania are present on mainland Australia. The Tasmanian Temperate Forest ecoregion represents a link between the dry mainland and cool, wet western Tasmania, which has pronounced Gondwanan affinities. However, this ecoregion is of interest in its own right. Twenty-six of the 29 eucalypts native to Tasmania and approximately half of Tasmania’s vascular plants can be found in dry sclerophyll forest. Understory diversity is high, and the diversity in composition and structure of vegetation is reflected by the abundance and diversity of its fauna. Endemism in the vascular flora increases with distance from Bass Strait, as elevation increases, and as geological uniqueness increases (Duncan 1999).

A rich mammalian fauna utilizes the mixed sclerophyll forests and heath vegetation of Tasmanian Temperate Forests. Perhaps the most renowned of these is the largest marsupial carnivore, the Tasmanian thylacine (Thylacinus cynocephalus), which was hunted to extinction by European settlers. Both the thylacine and the Tasmanian devil (Sarcophilus harrisii) were once widespread on mainland Australia, but were eliminated before the arrival of Europeans, presumably through competition with the dingo (Canis lupus dingo), which has never been introduced to Tasmania (Strahan 1998).

Other mammals found here include the echinda, or spiny anteater (Tachyglossus aculeatus), which is widespread in Tasmania but prefers sclerophyll and heathland areas. Australia’s other monotreme, the duck-billed platypus (Ornithorhynchus anatimus) is found in freshwater throughout Tasmania, including King Island but not the Furneaux Group. The long-nosed potoroo (Potorous tridactylus) is widespread on Tasmania, whereas the Tasmanian bettong (Bettongia gaimardi) is restricted to dry sclerophyll forest in eastern Tasmania, and the little pygmy possum (Cercartetus lepidus) prefers dry sclerophyll forest as well. Nearly extinct on the mainland, the eastern barred bandicoot (Perameles gunnii) inhabits grasslands through out this ecoregion. Both the spotted-tail (Dasyurus maculatus) and eastern quoll (D. viverrinus) are found here, as are larger herbivores, the red-necked wallaby (Macropus rufogriseus) and the eastern grey kangaroo (Macropus giganteus). Although abundant on mainland Australia, the eastern grey kangaroo has suffered a severe constriction of habitat on Tasmania after agricultural development. Wombats (Vombatus ursinus tasmaniensis) are widespread on Tasmania, with a separate subspecies on Flinders Island, V.u. ursinus.

The avifauna of the Tasmanian Temperate Forests includes several endemics and two species considered vulnerable by the IUCN: the swift parrot (Lathamus discolor) and the forty-spotted pardalote (Pardalotus quadragintus) (Hilton-Taylor 2000). Overhunting by humans caused the extinction of both the King Island emu (Dromaius ater) and the Tasmanian subspecies of emu, D. novaehollandiae diemenensis. The Tasmanian native hen (Gallinula mortierii), black-headed honeyeater (Melithreptus affinis), and yellow wattlebird (Anthochaera paradoxa) are near-endemic to this ecoregion. Several other species restricted to Tasmania and Bass Strait Islands also occur here, including the green rosella (Platycercus caledonicus), brown scrubwren (Sericornis humilis), and yellow-throated honeyeater (Lichenostomus flavicollis).

Rawlinson's window-eyed skink (Pseudemoia rawlinsoni) is endemic to the Tasmanian Temperate Forests, and approximately another ten lizard species occur here, including the little known mountain dragon (Tympanocryptis diemensis). Two amphibians are endemic to this ecoregion, the Tasmanian treefrog (Litoria burrowsi) and the Tasmanian froglet (Crinia tasmaniensis).

Current Status Tasmanian Aborigines first arrived in Tasmania 38,000 years ago, although there is no evidence of permanent settlement on the Bass Strait Islands. Approximately 12,000 years ago, they vacated the cold western half of the island for the coastline and the eastern half of Tasmania. Fire-stick farming practices, used to enhance grazing and hunting greatly modified the vegetation. European settlement has had even more profoundly disastrous consequences both on the mainland and the Bass Strait Islands. The islands of the Bass Strait were one of the first regions in Australia to be settled - in the late 18th and early 19th centuries. Arrival of European settlers on these islands had devastating consequences for marine mammal populations, native vegetation, and landbirds such as the King Island emu (Hope 1974).

As a result of European occupation, the Tasmanian Temperate Forests have suffered more irreversible disturbance than any other ecoregion on Tasmania. Today, between 30 to 40 percent of the dry sclerophyll vegetation present in 1803 has been completely transformed by agriculture, urbanization, and intensive forestry (Duncan 1999). The coastal areas on the Furneaux Group have been heavily modified by grazing (Thackway and Cresswell 1995). A significant amount of land in this ecoregion is privately owned (Duncan 1999, Thackway and Cresswell 1995). Approximately 15 percent of Tasmania’s dry sclerophyll forest is included in protected areas, although this figure includes outlying pockets of dry sclerophyll vegetation in other ecoregions (Duncan 1999). Key protected areas in the Tasmanian Temperate Forest ecoregion include the Douglas-Aspley, Strezlecki, Ben Lomond, and Freycinet National Parks (Brown and Podger 1999).

Types and Severity of ThreatsLarge portions of this ecoregion are privately owned, and may be lost without effective initiatives to conserve habitat on private land. Current land use in the Tasmanian Temperate Forest ecoregion includes forestry, mining, and grazing. Forestry often involves the destruction of old-growth eucalyptus forest and replacement with monoculture plantations. Habitat fragmentation, Phytophthora root-rot, and alien species are all threats. The fire regime for this ecoregion is also complicated: certain species, such as Allocasuarina and Callitris spp., may be endangered by high fire frequency, whereas other communities need frequent burning and have been altered by the cessation of Aboriginal fire practices.

Justification of Ecoregion DelineationThe Tasmanian Temperate Forest ecoregion includes three IBRA’s: ‘Ben Lomond’, ‘Freycinet’, and ‘Furneaux’ (Thackway and Cresswell 1995) and also includes King Island in the Bass Strait.

Strahan, R. 1998. The mammals of Australia. Australian Museum/Reed New Holland. Syndey, Australia.

Thackway, R. and I. D. Cresswell. editors. 1995. An Interim Biogeographic Regionalisation for Australia: a framework for establishing the national system of reserves, Version 4.0. Australian Nature Conservation Agency, Canberra.